The invention relates to an internal diameter measuring device for pipes which comprises a guide body slidably movable in the longitudinal direction in the pipe to be measured, which guide body is rotatable about the pipe axis. The device includes a plurality of feeler members or fingers which project past the exterior periphey of the guide body and which resiliently abut against the internal wall surface of the pipe to be measured. The feelers are adapted to transmit measuring values to an evaluating unit which amplifies the values and transmits them further.
A device of this type is known and is for example described in the German utility model No. 7,502,220. Such device serves preferably for carrying out tolerance measurements in the bores of machine tools. Such devices are not suitable for measuring diameters of long pipes, since the device only can be manually manipulated by means of a handle and the measurement evaluation unit is solely provided with a scale of an indicating device. Measurements carried out with this type of a device are quite time consuming. An automatized measurement and evaluation of the measured values is not possible with a device of this type. Furthermore, in view of the minimum size that is mandated by the construction of this type of device, the feelers thereof can carry out only the measurements of the internal wall of a pipe at points spaced a considerable distance from each other and therefore small openings or depressions in the internal wall surface of the pipe, for example so-called washed-out areas in gun barrels cannot be measured at all with this type of a device.